biology questions?

[steven_loves_sarah]

- homeostatic system comprise components such as sensors, effectors and variables. in such systems the component being kept relatively constant is
a: the variable
b: input to the sensor
c: input to the effectors
dutput from the effectors.

-Insulin is a peptide hormone produced and relased by the beta cells of the pancreas as a response to high glucose levels. insulin would be transported across the plama membrane of these beta cells by?
a: the process of endocytosis
b; active transport through prtein channels.
c: dissolving in the lipid bilayer
d: the process of exocytosis

- which one of the following statements best describes homeostasis in animals? Homeostatis is the process in which animals
a: maintain their blood levels at a constant level
b:survive a changing enviroment.
c: maintain a constant internal enviroment for their cells
d: maintain a constant internal and external environment for their optimal physiological functioning.